Modern film photography provides both amateurs and professionals with high resolution photographic prints. For example, using a popular 35 millimeter film format, cameras capture scene images on the film, which is subsequently developed into negatives by immersing the film in a sequence of suitable wet chemical baths. Light is projected through the negative onto photosensitive print paper, which is developed into a high resolution photographic print using another sequence of wet chemical baths. Dry, solid state photorecording processes provide advantages since they operate independent of any wet chemical baths.
Various methods of solid state photorecording of a scene are known. One method comprises directly imaging the scene onto a sheet of storage phosphor particles. Such storage phosphors particles have acceptable light sensitivity equivalent to some types of photographic film. Unfortunately, a portion of light of an image incident upon each phosphor particle is scattered to adjacent phosphor particles, degrading resolution of the stored image. Since the storage phosphor particles are relatively large particles, typically in a range five to ten microns in diameter, they scatter more light than some other smaller particles. A minimum particle size is limited because there is an undesirable decrease in luminescent efficiency as storage phosphor particles are made smaller than approximately five microns in diameter.
Image resolution is especially degraded when storing a high contrast image, which includes a very bright region adjacent to a very dark region. Storage phosphors that correspond to the very bright image region scatter a large amount light to adjacent storage phosphors that correspond to the very dark image region. Accordingly, the image recorded by the storage phosphors includes a bright region that has bled over to obscure an adjacent dark region.
Another solid state photorecording method comprises directly imaging the scene onto a Charge Coupled Device (CCD) and storing in a memory device electrical signals produced by the CCD in response to the imaged scene. While simple CCD's having a small number of pixels are easily available at low cost, manufacturing difficulties limit availability and increase cost of complex CCD's having a large number of pixels, such as more than one million pixels.
What is needed is a simplified, cost effective optical apparatus for solid state photorecording of optical images with enhanced resolution.